Glaucoma is a disease of the eye in which intraocular pressure rises to abnormal levels. In the human eye, a fluid called the aqueous humor functions to maintain the pressure in the eye at a level slightly above atmospheric pressure: a normal intraocular pressure is about 15 mm Hg gauge. The aqueous humor keeps the globe of the eye firm and provides nutrition for the lens and the cornea. The aqueous humor is constantly secreted by the ciliary body and is drained away at the base of the iris via a series of channels known as the trabecular meshwork. When these outflow channels become blocked, the pressure in the eye increases and the circulation of blood to the optic nerve and other parts of the eye is restricted. Such a condition is known as glaucoma. If the intraocular pressure remains elevated for prolonged time periods, the fibers of the optic nerve may atrophy and the retina may lose function.
Current methods for relieving intraocular pressure increases in the eye include various types of eyedrops such as beta-adrenergic blocking agents, sympathomimetic agents, miotics, alpha II selective agents, carbonic anhydrase inhibitors and prostaglandin agents. Tables of some of these agents appear in the Physician's Desk Reference in Ophthalmology 2000, pages 11–12. These medications work to lower the intraocular pressure by either reducing aqueous humor formation or by increasing the amount of aqueous humor outflow (removal) from the anterior chamber of the eye.
Such methods for relieving the intraocular pressure are often undesirable due to the side effects of many of these drugs. For example, carbonic anhydrase inhibitors may cause lethargy and, in some instances, disorientation. Beta-blocker medications may be contraindicated in patients with breathing problems or slow heart rates. An increase in blood pressure may result from sympathomimetic drugs. Finally, parasympathomimetic drugs may be associated with retinal detachments in eyes with peripheral retinal and retinovascular diseases.
Therefore, there remains a need in the art for a method of relieving intraocular pressure in glaucoma patients without afflicting the patient with a variety of undesirable side effects.